1. Technical Field of the Invention
The present invention relates to an electric power converter that has a plurality of semiconductor modules having integral semiconductor elements and a capacitor as a power source connected to the semiconductor modules.
2. Description of the Related Art
Electric power converters such as an inverter and a converter convert electric power by switching a plurality of semiconductor elements (switching elements).
There exist high-voltage-side semiconductor elements and low-voltage-side semiconductor elements connected mutually, A capacitor, which serves as a power source, is connected to electrode terminals of the semiconductor elements opposite to the sides where the semiconductor elements are connected mutually. In addition, the semiconductor elements and the capacitor are connected by bus bars.
Thereby, one closed circuit is formed with the pair of semiconductor elements, the capacitor, and the plurality of bus bars.
Further, the current that flows to the closed circuit changes when switching the semiconductor elements (refer to the first embodiment, FIG. 11 and FIG. 12 of Japanese Patent Application Laid-Open Publication No. 2008-253055).
When the impedance in the closed circuit is high at this time, a large surge voltage arises and there is a possibility of causing damage to the semiconductor elements.
Then, the technology of reducing the inductance in the above-mentioned closed circuit by making an area inside a closed circuit small is disclosed in Japanese Patent Application Laid-Open Publications No. 2002-253055 and No. 2006-2959 97.
However, if the circuit has the composition that the current flows mutually in the same direction in parts of conductive parts adjoining the closed circuits, the inductance of the parts will become large even if the area inside the closed circuit is made small.
Consequently, there is a possibility that it may become difficult to fully control the surge voltage.